Experimental transportation and sedimentation of micro-proppant in a vertical rough fracture model with operational factors

Since hydraulic fracturing became widely adopted and commercialized, most studies on proppant transport have focused on conventional-sized proppants (CPs) (20/40-mesh, 40/70-mesh, and 70/140-mesh) in fracture models. To support branch fractures and micro-fractures, micro-proppants (MPs) larger than 100 mesh have been introduced. However, the transport mechanisms for proppants with different particle diameters are not yet well understood. In this study, a visual flat panel model was employed to investigate MP transport in natural fractures under varying conditions of viscosity, fluid velocity, concentration, and particle size. The results demonstrated that, compared to conventional proppant, MPs struggle to form immobile dunes in fractures. Furthermore, the dunes they form are more easily displaced by slick water. As particle size decreases, the viscosity required for MP transport decreases. However, increasing viscosity further enhances the ability of MP to move through rough fractures. In rough fractures, reducing particle size is more effective than increasing pump rates in facilitating the transport of proppant to distal regions. These findings provide valuable insights for optimizing MP parameters in field applications to better alleviate the decline in shale hydrocarbon production.